DESCRIPTION: Aging is associated with body composition changes that include a greatly reduced skeletal muscle mass. A reduction in muscle mass is a cause of the age-associated decrease in basal metabolic rate, strength, levels of physical activity, energy requirements, which, in turn, contributes to increased body fatness and abdominal obesity often seen in the elderly. These factors contribute to an increased risk for many age-related disorders, including non-insulin dependent diabetes mellitus (NIDDM), and impaired functional mobility. Older women, with higher amounts of fat mass and lower amounts of FFM and muscle mass than men, are at the greatest risk of developing NIDDM and the vast array of complications associated with abnormal glucose metabolism. The most common recommendation for overweight women with NIDDM or at risk for this disease is weight loss and increased physical activity. However, the common practice of severe dietary restriction can compromise nutrition and metabolic status and result in significant losses of fat free mass. Because of their low levels of physical activity, sedentary older women have extreme difficulty losing weight. In addition, weight loss and improvement in metabolic status is rarely permanent. These investigators propose to test the hypothesis that moderate, short term weight loss will result in a significant improvement in insulin action. Further, they will test the hypothesis that moderate, short term weight loss when combined with resistance training (RT) will result in a preservation of fat free mass, basal metabolic rate and a greater improvement in insulin action than the diet alone. They propose to examine the effects of a 4 wk 500 kcal/d deficit diet alone or in combination with a high intensity RT program on insulin action, body composition, and basal metabolic rate in moderately overweight women between the ages of 60 and 75 years. Insulin action will be assessed via the hyperinsulinemic-euglycemic clamp technique (insulin infusion rate of 40 mU/m2/min). BMR will be measured by indirect calorimetry. Fat and muscle cross-sectional area changes will be assessed by CT scan. Whole body composition, and muscle strength and function will be quantified. Strict dietary control will be maintained by providing energy-defined menus at the Nutrition, Metabolism, and Exercise Laboratory. This study hopes to provide new and important information about effective therapies for the treatment of obesity, impaired glucose tolerance and NIDDM.